Conventionally, plasma display panels (referred to below as “PDP”) are widely used in the field of display devices, and recently there have been demands for large-screen PDPs which have excellent quality but are low in cost.
PDPs are formed by laminating a front substrate and a rear substrate via a sealing material, and an electrical discharge gas is sealed thereinside. Three-electrode surface discharge technology is commonly used for PDPs in which sustaining electrodes and scanning electrodes are formed on the front substrate, and address electrodes are formed on the rear substrate. When voltage is applied between the scanning electrodes and the address electrodes so as to generate an electrical discharge, the sealed electrical discharge gas converted into plasma and ultraviolet rays are discharged. Phosphors which are formed on the rear substrate are excited by the ultraviolet rays resulting in visible light being discharged.
A process for manufacturing a PDP generally includes a step of forming a front substrate and a rear substrate separately (i.e., a front substrate step and a rear substrate step), and a step of laminating the two substrates together (i.e., a panel formation step). In the manufacturing process, during a period from when a protective film has been formed on the front substrate to protect it against plasma electrical discharge until the front substrate and rear substrate are laminated together, impurity gases such as H2, H2O, CO, N2, and CO2 may be adsorbed by the protective film. If these impurity gases are adsorbed to the protective film, there is a resulting reduction in the secondary electron discharge coefficient of the protective film. As a result, there is a possibility of the discharge voltage of the PDP increasing. In view of this, in the sealing step to seal together the two substrates, an exhaust pipe is attached and the interior of the panel is purified (i.e., dried) by heating and evacuating (i.e., by means of vacuum baking). Moreover, aging (i.e., pre-conditioning) is also performed by applying AC voltage to the electrical discharge gas after it has been introduced so as to generate an electrical discharge, and to then reduce the discharge voltage of the panel so as to stabilize the electrical discharge characteristics (see, for example, Patent document 1).
[Patent document 1] Japanese Patent Publication No. 3830288